Transmembrane Protease, Serine 11B (TMPRSS11B)

TMPRSS11B is a type-II transmembrane protease, similar to hepsin (TMPRSS1). TMPRSS11B is a member of a larger family of membrane attached serine proteases, a poorly defined group that includes TMPRSS11A, B, C, D, E, F, Hepsin, Corin, Matriptase-1, 2 and 3. The highest degree of identity is with TMPRSS11A, which shares 40% identity at the amino acid level. TMPRSS11B has a domain structure of an aminoterminal cytoplasmic domain, followed by a transmembrane domain, a SEA domain (Sea urchin sperm protein, Enterokinase, Agrin), a short spacer, then the trypsin-like serine protease domain. The SEA domain is thought to play a role in carbohydrate binding in the analogous protein sequences where it is found, but the role in TMPRSS11B is unclear. The cleavage of the Arg184-Ile184 bond is thought to liberate the catalytic domain.